1. Field of the Invention
The present invention relates to a thumb double key, commonly called a Briccialdi B/B flat mechanism, in other words a mechanism operating the tones B and B flat, for a woodwind instrument, such as a flute or piccolo. Such a mechanism comprises a B key comprising a cup part and a lever part, the B key being rockingly movable around an axle, and a lever rockingly movable around the same axle and capable of transferring the rocking motion to the B key so as to close the B key and at the same time to a B flat key so as to close the B flat key.
2. Description of the Prior Art
The known Briccialdi B/B flat thumb key or lever mechanism is designed such that the rocking motion of the double key takes place by means of two charnier tubes mounted on an axle which is arranged at right angles to the longitudinal axis of the instrument.
The transmission of the rocking motion of the double key to the B-flat key on the main axle is effected by means of a simple system of levers between the back-connecting levers of the said keys.
The Briccialdi B flat thumb key mechanism consists of the two levers arranged parallelly at right angles to the above-mentioned longitudinal axle. The B key function applies to one of the levers. The other lever arranged above the B key but on the same axle acts such that any pressure on this lever causes a simultaneous closure of the B flat key on the main axle by means of the above-mentioned back-connecting levers. The springs of the mechanism are flat springs attached to the levers. The flat springs are arranged in the longitudinal direction of the levers and slide on the surface of the instrument tube which is normally made of a noble metal. The pressure exerted by the springs on the tube determines how fast the rocking motion of the levers can get.
This known design incurs a number of disadvantages, especially friction, less than optimal stability and slackness in the function of the key. Thus, the geometrical conformation of the flat springs attached to the levers is not optimal to their purpose, and it is known that there can be significant friction between the ends of the springs and the surface of the instrument tube on which they slide. This non-optimal conformation with a sliding movement and the friction caused hereby therefore limit how fast the rocking motion of the levers can get and thereby limit the artistic freedom of the musician. Furthermore, the difference in the action between the flat springs of the conventional Briccialdi double key and the needle springs used at all other keys gives an undesired difference in the tactile action between the Briccialdi keys and all other keys and thereby an unevenness in the tactile feel of the instrument as a whole.